Doxorubicin (DOX) is a cardiotoxic drug. To reduce the harmful effects of DOX, two plant‐derived components, including curcumin (CUR) and carvacrol (CAR), were considered. This study aimed to assess the protective effects of CUR and CAR on DOX‐induced cardiotoxicity using physiological and stereological evaluations. Male rats were randomly allocated to six groups. Group's I‐VI received phosphate‐buffered saline (PBS), CUR (100 mg kg⁻¹ day⁻¹), CAR (50 mg kg⁻¹ day⁻¹), DOX (4 mg kg⁻¹ week⁻¹), DOX‐CUR, and DOX‐CAR, respectively. On day 24, plasma troponin I and ECG were analyzed and the left ventricle underwent stereological assessment. The results showed a fivefold increase in troponin I in the DOX‐treated animals compared to the PBS ones. Additionally, heart rate and QRS amplitude, respectively, reduced by 18% and 31% and QT interval and QRS duration, respectively, increased by 41% and 24% in the DOX group in comparison with the PBS rats ( p < .05). The total volume of the myocardium and vessels and the number of cardiomyocyte nuclei also, respectively, decreased by 30%, 45%, and 43% in the DOX group compared to the PBS animals (atrophy of the ventricular tissues, p < .01). Besides, the mean volumes of the connective tissue and cardiomyocytes, respectively, increased by 46% and 52% in the DOX group ( p < .01). In the DOX‐CUR and DOX‐CAR groups, the changes were prevented extensively in comparison with the DOX group ( p < .01). Co‐administration of CUR or CAR and doxorubicin for 24 days could improve the heart function and structural changes.